CO_2腐蚀产物膜形态结构与温度和压力的关系

在高温高压静态釜中对3种油套钢N80、P110和J55的CO2腐蚀进行了模拟腐蚀试验。 结果显示,在试验条件下,3种材料腐蚀产物膜的断面形貌显示出双层结构,表层是晶体规整的 结晶状态,表层与基体之间为类似泥浆状的固体薄层;3种材料在模拟采出液中腐蚀产物膜的厚 度和晶粒大小随着温度的变化情形大致相似,在120℃时均达到了最大,而极小值并不相同;膜 厚和晶粒大小的极大值或极小值所对应的温度3种材料均相同;3种材料的腐蚀产物膜厚度或表 面晶粒大小随CO2分压变化规律大致相近,在CO2分压为6.89MPa时,均达到最大,在超临界 压力以上急剧减小,其间出现了2峰1谷,在峰值或低谷处3种材料存在异同;90℃时CO2分压 在超临界状态下3种材料腐蚀产物膜的厚度和晶粒大小均较小。

Effect of temperature and pressure on profile of C0_2 corrosion scales on oil well steels

The corrosion process of three kinds of oil well steels in C0 2 environment with varying temperature and C0 2 partial pressure is simulated by means of static autoclave.And the effect of temperature and C0 2 partial pressure on thickness and grain size of the scales is studied by using Scanning Electron Microscope(SEM).The results show that,the cross-sections ofthe corrosion product scales of the three kinds of steels are double.1ayered in structure.The variation of scale thickness ofthe steels with respect to the temperature is in the same pattern,of which the maximum scale thickness appears at 120℃,while the minimum of the scale thickness is variant for tllethree steels.The variations of the grain size with respect to the temperature for the three steels exhibit a peak and a valley.Thetemperatures and grain size corresponding to the peak andvalley for different materials vary,but the temperatures corresponding to the peak and valley of scale thickness are the same for the three steels.The variation of scale thickness for the three kinds of steels with C0 2 partial pressure is also in the similar pattern,of which the maximum scale thickness appears at the C0 2 partial pressure about 6.89 MPa,and then decreased rapidly.The variations of grain size with C0 2 partial pressure for the three steels exhibit two peaks and a valley.However the C0 2 partial pressures and grain sizes corresponding to the peaks and valley for different materials vary,and grain sizes of the three steels with C0 2 partial pressure decreased quickly beyondthepeaks.